In cycling, it is indispensable for maximum cycling advantage, for the cyclist to fix his or her feet to the pedals of the bicycle. This, of course, enables the cyclist to apply to the crank of the drive sprocket, a pedaling action not only during the descent of one of the pedals, but also during the ascent of the other pedal.
One conventional way of affixing a shoe to a pedal provides the pedal with a cage or clip which is open toward the rear and into which the cyclist inserts the toe of a shoe. The shoe is held in place by a strap which closes the cage.
This system is not entirely satisfactory since it requires some effort on the part of the cyclist to engage or disengage the foot or the shoe from the cage and manual operation of the strap. Furthermore, since the strap must be tightened, there is a constriction of the foot which interferes with the comfort of the cyclist and the performance of the cyclist. Furthermore, the cyclist cannot readily and rapidly disengage the foot from the pedal, thereby posing a danger, especially in the case of a fall.
There are pedal attachment systems in which a pedal is provided at its front end with a stop and a lever is pivotal at the rear end. The stop at the front end engages a front edge of a plate fixed on a shoe or foot and the lever engages over a rear edge of the plate. The clamping of the shoe on the pedal is effected automatically upon the application of foot pressure and the manner in which the shoe is engaged is generally similar to that which applies for automatic ski bindings.
Because the front stop has the configuration of a cylindrical surface, it is possible to release the engagement of the plate in the pedal by rotating the foot outwardly or inwardly to swing the front end of the plate free.
This has the advantage that it allows automatic engagement of the shoe in the pedal but yet permits rapid disengagement in the case of a fall by a slight movement toward the interior or exterior.
Another advantage of this system is that the foot of the cyclist is not compressed by a strap of a cage and thus the latter device for the retention of the shoe on the pedal is frequently more comfortable use.
Nevertheless, this arrangement has the drawback that each foot of the cyclist must be fixed along the axis of the pedal and that it is not possible for the foot to move angularly during pedaling. An angular displacement, of course, may release the pedal. However, some angular displaceability without such release is important because different morphologies of cyclists mandate that the foot be inclined to the axis of the pedal in one or another direction in the course of use. In some cases, an orientation of the foot at an inclination to the axis may be fixed while in other cases, for most effective pedaling action, a certain latitude of pivotal action of the foot relative to the pedal body is essential or desirable. The latter is the case especially when the cyclist is in a "dancing" position on the bicycle or where the bicycle is subjected to lateral oscillations.